Relationship between LAPTM4B gene polymorphism and susceptibility of gastric cancer.

BACKGROUND

A novel gene called LAPTM4B (lysosome-associated protein transmembrane 4beta) was mapped to 8q22, and contains seven exons. The 2.25-kb messenger RNA of the gene encodes a putative lysosome-associated protein with four transmembrane regions. There are two alleles of the gene, named as LAPTM4B1 and LAPTM4B2. Allele *1 differs from allele *2 in that it contains only one copy of a 19-bp sequence in the 5' untranslated region (UTR), whereas this sequence is duplicated and tandemly arranged in allele *2. Studies showed that the allelic variation of LAPTM4B was associated with the genetic susceptibility of hepatocellular carcinoma but not with that of esophageal squamous cell carcinoma. This study was designed to investigate the possible association between the allelic variation of LAPTM4B and the genetic susceptibility of gastric cancer.

MATERIALS AND METHODS

The genotype of LAPTM4B was analyzed in 350 unrelated healthy adult individuals and 214 patients with gastric cancer by utilizing polymerase chain reaction based on specific primers. The genotypic distribution of LAPTM4B was analyzed by chi(2) test.

RESULTS

The allelic frequencies of the *2 were 33.88% and 24.14% in the gastric cancer group and the healthy control group, respectively, which was significantly different between the two groups (P < 0.001). There was a significant difference in the overall genotypic distribution between the patients and the controls (P = 0.023). The risk of suffering from gastric cancer was increased 1.819 times in the individuals of the *1/2 genotype [95% confidence interval (CI) 1.273-2.601] and 2.387 times in the individuals of the *2/2 genotype of LAPTM4B (95% CI 1.195-4.767) compared with the *1/1 genotype. No association between the genotypic distribution of LAPTM4B and the clinical information on patients of gastric cancer such as age, pathological type, differentiation classification of TNM, and infection of hepatitis B virus was shown.

CONCLUSION

This study indicated that allele *2 of LAPTM4B might be the risk factor of gastric cancer, which could be associated with genetic susceptibility of gastric cancer.